Issue 22, 2008

Reactivity of nanocolloidal particles γ-Fe2O3 at the charged interfaces

Part 1. The approach of particles to an electrode

Abstract

We are interested here in the reactivity of magnetic nanoparticles at the electrode–electrolyte interface with the aim of the electrochemical synthesis of magnetic and conductive liquids (electronic conduction). The reactivity of charged colloidal particles occurs through a two steps process, the first being the approach toward the electrode with a possible adsorption phenomenon and the second step, the electron transfer. In this first paper we focus on the approach and the deposition of well-defined γ-Fe2O3nanoparticles onto conductive substrates like mercury and gold under different conditions in order to vary the interactions particle/substrate especially the electrostatic interactions. The approach of the particles near the electrodes is estimated from the electrochemical currents related to the transformation of the particles. This electrochemical method is validated by coupling several techniques on gold electrodes: direct imaging by atomic force microscopy and study of kinetics by reflectometry. The results show that the electrochemical currents are always associated to adsorption of the particles, so that the electrochemical method can be used to estimate the adsorption of the particles, thus to follow the kinetics. The influence of the electrostatics on the occurrence of adsorption highly depends on the nature of the substrate and on the nature of the colloidal suspension. (ions, pH, ionic strength): whereas electrostatics governs the deposits in some cases, it is totally dominated by other interactions in other cases. Therefore, it seems difficult to predict a priori the existence of adsorption. However, when a deposit occurs, the kinetics and the maximal coverage of the substrates are controlled by the electrostatic interactions between the particles already adsorbed and those, close to the interface, in the bulk of the solution.

Graphical abstract: Reactivity of nanocolloidal particles γ-Fe2O3 at the charged interfaces Part 1. The approach of particles to an electrode

Article information

Article type
Paper
Submitted
04 Dec 2007
Accepted
27 Mar 2008
First published
23 Apr 2008

Phys. Chem. Chem. Phys., 2008,10, 3263-3273

Reactivity of nanocolloidal particles γ-Fe2O3 at the charged interfaces

I. T. Lucas, E. Dubois, J. Chevalet and S. Durand-Vidal, Phys. Chem. Chem. Phys., 2008, 10, 3263 DOI: 10.1039/B718593F

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